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Published October 1, 1998 | Published + Submitted
Journal Article Open

Keck Spectroscopy and NICMOS Photometry of a Redshift z = 5.60 Galaxy


We present Keck Low Resolution Imaging Spectrometer spectroscopy along with Near-Infrared Camera and Multiobject Spectrometer (NICMOS) F110W (~J) and F160W (~H) images of the galaxy HDF 4-473.0 in the Hubble Deep Field (HDF), with a detection of an emission line consistent with Lyα at a redshift of z=5.60. Attention to this object as a high-redshift galaxy was first drawn by Lanzetta, Yahil, & Fernandez-Soto and appeared in their initial list of galaxies with redshifts estimated from the Wide Field Planetary Camera 2 (WFPC2) HDF photometry. It was selected by us for spectroscopic observation, along with others in the HDF, on the basis of the NICMOS F110W and F160W and WFPC2 photometry. For H_0=65 km s^(-1) Mpc^(-1) and q_0=0.125, the use of simple evolutionary models along with the F814W (~I), F110W, and F160W magnitudes allow us to estimate the star formation rate (~13 M_☉ yr^(-1)). The colors suggest a reddening of E(B-V)~0.06. The measured flux in the Lyα line is approximately 1.0×10^(−17) ergs cm^(-2) s^(-1), and the rest-frame equivalent width, correcting for the absorption caused by intervening H I, is ~90 Å. The galaxy is compact and regular, but resolved, with an observed FWHM of ~0."44. Simple evolutionary models can accurately reproduce the colors, and these models predict the Lyα flux to within a factor of 2. Using this object as a template shifted to higher redshifts, we calculate the magnitudes through the F814W and two NICMOS passbands for galaxies at redshifts 6<z<10.

Additional Information

© 1998 American Astronomical Society. Received 17 July 1998. Accepted 6 August 1998. Published 31 August 1998. The near-infrared observations are supported by NASA grant NAG5-3042 to the NICMOS instrument definition team. R. J. W. thanks the W. M. Keck Observatory and the Lick Observatory for their hospitality during the period when this work was carried out and P. McCarthy and D. Koo for useful discussions. A. B. and L. J. S. L. gratefully acknowledge financial support from NICMOS postdoctoral positions.

Attached Files

Published - Weymann_1998_ApJ_505_L95.pdf

Submitted - 9807208.pdf


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